It shouldnt bother people because the number of the devil is actually 616 not 666.

Documents have been found where the number of the devil was 616, also an explorer found one of these documents and saw the number was 616, he didnt think it could be right so he changed the number to 666, the modern number of the devil.

As far as the DaVinci code is concerned, people just have to take the information with a pinch of salt, none of it has been proven.